Substituted alkyl 3-chlorosulfonylthiophene-2-carboxylates are of considerable interest in the preparation of pharmaceuticals and herbicides. U.S. Pat. No. 4,224,445 issued Sept. 23, 1980 to Hromatka et al. discloses the utility of these intermediates in the preparation of compounds possessing anti-inflammatory, analgesic, and antirheumatic activity. European Patent Application No. 30142 discloses herbicidal sulfonyl urea compounds derived from substituted alkyl 3-chlorosulfonylthiophene-2-carboxylates.
Therefore it is of great importance to develop economically attractive processes to substituted alkyl 3-chlorosulfonylthiophene-2-carboxylates that involve few chemical steps, with easy to carry out operations, and utilize inexpensive starting materials and reagents.
U.S. Pat. No. 4,230,873 issued Oct. 28, 1980 to Hromatka et al. discloses a multistep process leading to substituted alkyl 3-chlorosulfonylthiophene-2-carboxylates which involves converting the 3 hydroxythiophene-2-carboxylic acid methyl ester. This process, in addition to its many steps, is encumbered by the usage of large quantities of such reagents as PCl.sub.5 and SOCl.sub.2 which result in severe waste disposal problems.